Compaction index

ABSTRACT

In compacting an asphalt layer which is continuously deposited by a paver machine, a compacting machine reciprocates behind the paver. With the aid of signals from sensors (3) for temperature, sensors (5) for movement velocity of the compacting machine, sensors (7) for change of path, and sensors (9) for static/vibratory compacting operation, a processor (1) determines the position of the compacting machine continuously in relation to the paver, and other variables for each area segment passed by the compacting machine. The position of the compacting machine is displayed symbolically on a monitor (19) and the variables measured and determined for each passed area segment are stored in a memory (17). For each passed area segment, a total index number can be determined for this area segment, which on the monitor (19) is displayed as a field having a color or light intensity which is proportional to this total index number. The index number indicates the total amount of compacting work which the compacting machine has made on this area segment. This position of a field representing such an area segment is displayed on the monitor (19) in a proportional scale.

FIELD OF THE INVENTION

The present invention is related to measurement and documentation ofresults of compacting work and to control of a rolling compactingmachine in the compacting of a deposited ground surface, in particularasphalt. It is related to methods and devices arranged on the compactingmachine for measurement, documentation and control of the compactingwork for ensuring a uniform result of the compacting work.

BACKGROUND OF THE INVENTION

For the compacting of earth there exists a plurality of equipment basedon various types of compaction gauges or measuring devices.Documentation is normally made by means of devices showing a summarizedpicture of the result. At the same time, the corresponding data isstored in some suitable medium. Further processing and entering of theobtained measured results in a suitable data base can then be performedin a personal computer arranged at another location. When compactingasphalt, the tested methods from the compacting of earth cannot betransferred without due consideration. This is true for primarily tworeasons:

1. It does not yet exist any functioning compaction measuring deviceshowing the result of the compacting of the asphalt layer as measuredcontinuously directly from the compacting machine. The nuclearmeasurement devices which are known and are to be mounted on thecompacting machine itself, have a limited use since they require longintegration time to produce accurate information and since the usethereof is impeded by the restrictions prescribed by the authoritiesowing to the radiation.

2. In compacting asphalt it is not possible to control the movement ofthe compacting machine, so that a large rectangular surface could becompacted to a finished state before the compacting machine is used forcompacting another large rectangular area. Instead, the compacting ofasphalt is performed continuously accompanying the deposition of theasphalt by an asphalt paving machine which can move forward continuouslywith an approximately uniform velocity over a distance which oftenseveral hundreds of meters. The paving operation is normally stoppedonly at breaks and if the supply of new asphalt compound fails.

In compacting asphalt the compacting machine follows the paver machineaccording to a scheme having limited possibilities of variation. Apostcompaction of some areas where a too low compaction degree has beendetected can only be performed if more than one compacting machine isavailable.

It is also advantageous to have access to equipment which can documentthe compacting work performed which together therewith stores allrelevant operational parameters.

Even if there would be limited possibilities of correcting mistakes byhaving the compacting machine afterwards compact badly worked asphaltportions it may be a great value if the system successively producescontinuous information by which it is possible to adjust thoseoperational parameters so that the result of the compacting work cansuccessively approach an optimum result. Adjustable parameters can bethe distance or stroke length over which the compacting machine travelsbefore it reverses its running direction to move in the oppositedirection; the interior operational parameters of the compactingmachine; and the velocity of the asphalt paver.

SUMMARY OF THE INVENTION

It is a purpose of the invention to provide a measurement of the degreeof compaction of a continuously deposited layer of a material.

It is a further purpose of the invention to provide documentation of thecompacting work when compacting a continuously deposited layer of amaterial.

It is a further purpose of the invention to provide a system forcontinuous information to an operator when compacting a continuouslydeposited layer of a material.

It is a further purpose of the invention to provide means for displayingparameters associated with the compacting work and the achievedcompaction effect when compacting a continuously deposited layer of amaterial, whereby an operator can adjust operational parameters in orderto achieve a desired compaction effect on each area segment passed.

According to the invention methods and devices are provided by means ofwhich the purposes mentioned above can be achieved.

In the measurement of the degree of compaction in a segment of adeposited layer of hot material, in particular asphalt compounds, whichcontinuously cools after the deposition thereof and is compacted bybeing repeatedly passed or run over by a compacting machine, for eachpass or run over the segment variables or parameters are determined. Thevariables as parameters are determined, by means of various measuringdevices and sensors arranged on the compacting machine. As a measurementof the compaction degree of a deposited segment layer, a total indexnumber is determined as a function of these variables for all the passesperformed. This index number function also depends on different fixed,exterior parameters such as the type of vibration of the compactingmachine, the type of material/asphalt compound, the thickness of thedeposited layer, the ground temperature, the temperature of the ambientair, and the wind velocity.

Preferably for each pass a partial index number is determined as afunction of the variables only for one pass. The total index number isthen determined as a function only of the sum of the partial indexnumbers for each pass. It can be observed that a sum of variables isequivalent to a product of exponentiated variables.

Further, preferably the temperature of the segment is measured at eachpass of the area segment such as by means of a thermometer arranged onthe compacting machine. The partial index numbers are then determined asa function of the temperature of the segment for the corresponding pass.The movement speed of the compacting machine is measured for each passand then the partial index number for an area segment can be determinedas a function of this movement speed at the corresponding pass of thearea segment.

For a vibrating compacting machine, and for each passed area segment thevibratory frequency and/or vibratory amplitude of the compacting machineis determined by means of suitable sensors on the compacting machine.The partial index number of an area segment can in this case bedetermined as a function of the vibratory frequency and/or the vibratoryamplitude respectively for the distance traveled by the compactingmachine over the area segment.

The predetermined function is in an advantageous embodiment of a productof functions, where each one depends on only one of the variablequantities. It should be pointed out that for logarithmical entities aproduct of the variables is equivalent to a sum.

The measurement can be used for controlling the compacting machine incompacting the layer which is in a hot state and is continuouslydeposited by a paving machine in front of the compacting machine. Thecompacting machine passes over the area behind the paver to compact thelayer just deposited. For each unit area of the layer deposited by thepaver which is passed by the compacting machine, the total index numberis determined as a function of the variables as measured for this unitarea and also of suitable operational parameters of the compactingmachine and fixed values for the layer of material. The travel of thecompacting machine over the individual areas and the operationalparameters of the compacting machine can be controlled by means of themeasured total index number, so that the total index number will achieveat least a predetermined value for each unit area.

In practical work the compacting machine passes over repeatedly the areabehind the paver machine and then a partial index number is determinedfor each unit area for each pass of the compacting machine over thisunit area as a function of the variable quantities measured for thisunit area and of the operational parameters of the compacting machineand of possible other fixed parameters. The total index number for eachunit area is calculated as the sum of the partial index numbersdetermined for each pass of the unit area.

The total index number is advantageously calculated continuously foreach unit area and further, it is displayed for an operator of thecompacting machine so that he will be able to control the compactingmachine as efficiently as possible. The total index number for each unitarea is then suitably shown on a monitor or display, located adjacent toa driver's place in the compacting machine, where the shape of thefields on the display correspond to and are proportional to the realposition of the unit area. The fields can be shown in light or colourintensity proportional to the total index number calculated for thisunit area or they can be shown in a colour scale. This color scale isarranged to correspond to the various possible total index numbers. Thecolour is chosen so that it corresponds to the calculated total indexnumber of the unit area.

Further, in suitable memory means, data is recorded about compacting thelayer, which is continuously deposited in front of and being compactedby a compacting machine which moves over the layer. Like above, sensorsand/or measurement devices are arranged for the measurement of variablesvalid only for each area segment passed by the compacting machine. Theposition of the compacting machine at each instant is calculated ormeasured. Further, memory means are arranged for storing, together withthe position of the compacting machine in coordinates for each areasegment passed by the compacting machine, data values representing themeasured variable quantities so that a data record comprising measuredvalues is obtained for each pass of each area segment.

Sensors and/or measurement devices comprise a measuring device arrangedon the compacting machine for measuring the surface temperature of thedeposited layer in the area segment which is just passed by thecompacting machine. The stored data values then comprise the temperaturemeasured by this sensor for each pass and for each area segment.

A measurement device can also be arranged for recording theinstantaneous movement velocity of the compacting machine where theposition of the compacting machine is calculated at each instant fromthe recorded movement speed of the compacting machine.

An indicator can further be arranged for indicating whether thecompacting machine vibrates and then the condition of vibration or novibration can be calculated in the stored data values.

When the compacting machine is vibrated or is of the vibratory type, asensor can be arranged for indicating the frequency and amplitude of thevibration and in this case the frequency and the amplitude of thevibration can be calculated in the data values stored for each areasegment.

From the variables determined for a pass, a partial index number can bedetermined as a function of the variables only for the one pass and thenthis partial index number can be stored.

A total index number can be determined as a function of the sum of(corresponds to the product for values which have been exponentiated)the partial index numbers for each pass. This total index number thencan be stored.

The temperature of the segment can be measured for each pass and thenthe partial index numbers can be determined as a function of thetemperature of the segment at the corresponding pass.

The movement velocity of the compacting machine can also be measured foreach pass and then the partial index numbers are determined as afunction of the temperature of the segment for the corresponding pass.

The movement velocity of the compacting machine can also be measured foreach pass and then the partial index numbers are determined as afunction also of the movement velocity for the corresponding pass.

A driver's interface for the control of a compacting machine whencompacting a layer which is continuously deposited by a paving machinemoving in front of the compacting machine, generally comprises; meansfor measuring, calculating and showing on a display at each instantsymbols representing the paver and the compacting machine itself; andthe position of these symbols in relation to each other beingproportional to the real positions of the compacting machine and thepaver. Further input means are provided for the driver's interfaceentering a start value for the compacting machine in relation to thepaver; a value for a correction; and a desired value for a laterdisplacement of the displayed symbol of the compacting machine inrelation to the paving machine. The symbol representing the paver isadvantageously fixedly located at a side or border of the monitor.

Suitably, the symbol representing the compacting machine on the displayhas a distance from the symbol representing the paver which isproportional to the real distance of the compacting machine from thepaver. The lateral position of the symbol representing the compactingmachine can be displayed as a position within one of several parallelelongated fields or paths, which extend in parallel to the depositiondirection of the layer up to the paver, perpendicularly thereto.

In a method for controlling and/or monitoring a compacting machine, inparticular the position thereof, in compacting a layer which iscontinuously deposited by a paving machine moving in front of thecompacting machine, the driver's interface can be used. The position ofthe compacting machine in relation to the paver is then shownsymbolically on a monitor at all times by a symbol representing thecompacting machine and a symbol representing the paver and the relativeposition of these symbols will proportionally represent the positions ofthe compacting machine and the paver in relation to each other. Anoperator will, by looking at the display, obtain information of therelative distance and the relative position of the compacting machine inrelation to the paver and can control the movement and/or operationalparameters of the compacting machine. For instance, the stroke length ofthe compacting machine within each path or lane can be ascertained whena change of path is to be performed so that the compacting machineperforms efficiently as possible to compact the deposited layer.

The instantaneous movement speed of the compacting machine can bemeasured and accordingly the position of the compacting machine at eachinstant can be determined by the movement speed as measured for thecompacting machine. This determined value is then used for a furtherdetermination of the position of the symbol representing the compactingmachine to be shown on the display.

In the case where the compacting machine moves reciprocally, in parallelto the deposition direction, up to the paver as in a direction backwardsfrom the paver, the position of the compacting machine in relation tothe paver can be continuously determined and shown on a display ormonitor. A symbol representing the compacting machine on the monitorwill have a distance from a symbol representing the paver which isproportional to the present distance of the compacting machine from thepaver. The lateral position of the compacting machine's symbol can beshown as a position within one of several parallel elongated fields orpaths extending in parallel to the depositing direction of the layer upto the paver.

In certain cases it can be assumed that the compacting machine changesits direction at substantially the same distance each time when itapproaches the paver machine and then the movement velocity of the pavercan be determined from those positions where the compacting machinechanges its direction close to the paver.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1A shows a block diagram of a device in a compacting machine forcontrol and documentation of the compaction of a deposited asphaltlayer,

FIG. 1B schematically shows the front portion of a compacting machine,

FIGS. 2A-2C show successive monitor pictures used for presentation ofresults and for control of the compacting machine,

FIGS. 3-5 show examples of weight curves for the compaction resultdepending on the temperature of the asphalt compound, on the movementvelocity and the vibratory frequency of the compacting machine,

FIG. 6 shows two diagrams, at the top the total index for consideredarea segment as a function in time and at the bottom the temperature ofthe asphalt compound within this area segment as a function of time,

FIG. 7 shows schematically the organization of a stored list ofcompaction data, and

FIG. 8 shows a diagram of a curve illustrating the compaction effects atsuccessive passes.

DESCRIPTION OF PREFERRED EMBODIMENT

A block diagram of a device for control and documentation of compactingwork in compacting a deposited layer such as asphalt is shown in FIG.1A. The device comprises various units arranged on and in a rollercompacting machine, see the item at 2 in the schematic picture of FIG.1B, the machine being the static, vibratory or oscillating type. Thecentral part of the device is a calculating unit or processor 1 locatedin some casing 4 in the compacting machine. The calculating unit 1receives, when the compacting machine 2 is running, continuouslyinformation from suitable sensors in respect of various parametersinfluencing the compacting of a deposited asphalt layer. They comprise athermometer 3 of IR-type, arranged on the compacting machine andmeasuring the surface temperature of the deposited mass close to thecompacting machine. A sensor 5 measures the movement velocity of thecompacting machine, which can be coupled to the drive motor of thecompacting machine, the driving wheels of the compacting machine, or tothe compacting roller itself. There is a steering sensor 7, generallycalled sensor for change of path or of lane, which can be arranged tosense the movements of the steering wheel or the angle of a steering rodhinge to detect such movements signifying a change of path or lane.Further there is a device or switch 9 indicating whether the compactingroller only performs a static compacting work or if it is vibrated. Inthe case where it is vibrated a signal is provided representing thefrequency and amplitude of the vibration, from sensors indicated at 8and 10 respectively. A sensor 11 can also be arranged for providing asignal representing a distance, i.e. the distance from the compactingmachine to a paving machine. The paving machine is supposed to workcontinuously in front of the compacting machine and deposit an asphaltlayer with an essentially uniform velocity. Finally there may also be aninput terminal or a receiver 12 to provide the processor 1 with wirelessconveyed information related to the movement velocity of the paver.

The calculating unit 1 has in addition access to stored and previouslyentered data in a memory unit 13. The data is entered from some unit 15,e.g. the shape of a keyboard and/or some magnetically readable mediumsuch as a memory card. In the latter case, the input unit 13 and thememory unit 15 can then be one device.

The calculating unit 1 performs for each unit segment or unit distance,over which it passes, for instance for a distance of one meter or twometers, calculations of (among other things) the position of thecompacting machine, in particular the position of the compacting machinein relation to the asphalt paver, by means of data obtained from thesensors 5 and 7. It may be considered that for this calculation alsoother kinds of sensors and systems can be used, which are not shownhere, for instance gyro sensors, receivers of GPS signals, positionsignals from fixedly placed total stations (target following geodeticstations for measurement of distance and angular position), etc. Variousdata for each passed segment of each path or lane are stored in a memoryunit 17 in the shape of a list which is schematically illustrated inFIG. 7. Certain actual data, also for earlier passed areas, are shown ona monitor 19 connected to the calculating unit 1.

In FIGS. 2A-2C successive monitor pictures are illustrated intended tobe shown on the monitor or the display 19 located in the driver's cabinin the compacting machine, not shown. The calculating unit 1 thuscalculates at all times (based on the velocity of the compacting machineas given by the signals from the velocity sensor 5 and information onstart and stop times and times for change of direction as obtained fromthe steering sensor 7) the position of the compacting machine inrelation to the paver. The paver machine is shown as an elongated field21 at the top of the elongated monitor picture, where field 21 has itslongitudinal direction located perpendicular to the longitudinaldirection of the entire monitor 19. Perpendicularly to the symbol 21representing the paver, parallel lines extend having an equal spacingand they thus extend in the longitudinal direction of the monitorpicture. This equal spacing represents substantially the compactingwidth which is obtained in the movement of the compacting machine overthe asphalt. The region between every two of these parallel lineslocated adjacent to each other represents the lanes or areas for thecompacting machine when performing the compacting work and the positionof the compacting machine is shown as a symbol 25 in such a path orlane. If a distance measurement device 11 is mounted on the compactingmachine, the output signal therefrom can be used for determining theposition of the compacting machine in relation to the paver, so that acorrect representation can be made on the display 19. It should beemphasized that the monitor picture at all times shows the relativeposition of the compacting machine in relation to the paver. A lengthscale, e.g. in meters, can be provided at the side of the displayedpicture, which shows the paths or lanes.

The total passed running distance of the compacting machine from thestart thereof is shown as an indication of a number of meters at 20within the field 21 symbolizing the paver. Checkpoints such as pegs orstakes or similar devices located at definite places adjacent to thedeposited material layer can be used for correcting this indication ofthe position of the paver.

Also other parameters can be shown on the display 19 such as thecalculated velocity of the compacting machine, or the velocity thereofas received by the unit 12, which can be shown with a suitable digit orfigure at 22 within the symbol 21 representing the paver. Thetemperature of the asphalt layer measured close to the compactingmachine in the shape of a suitable thermometer scale is shown at 27 andthe present velocity of the compacting machine, also shown in the shapeof a bar scale or thermometer scale at 29. On or adjacent to the displaymanual operating means are provided such as keys shown at 31, 34 for amanual displacement of the compacting machine symbol 25, so that theposition thereof can be corrected or for indication of a start positionat the beginning of the deposition of the asphalt layer or a start ofthe compacting operation as performed by the compacting machine. Furthera start and stop key 33 is arranged which is to be depressed by thedriver of the compacting machine at the start and stop of the paver.

The calculating unit 1 performs a calculation of the total effect of thecompaction on each unit area of the deposited asphalt layer. A unit areais here equivalent to each path or lane, over which the compactingmachine passes. The unit area will be recorded and a calculation is madefor fixed passed unit distances such as one or two meters. Generally thetotal compaction effect on a considered unit area results from the factthat a number of compacting machine passes have been made in differentconditions. Thus the temperature of the asphalt compound varies behindthe paver and the temperature falls gradually owing to the coolingeffect. The compaction effect for a single considered pass can beassumed to be a function of the temperature, of the rolling velocity ofthe compacting machine, and of constant parameters of the compactingmachine such as line load or roller charge, roller diameter, andvibratory data. The compaction effect in the different passes of thecompacting machine over this considered unit area can be assumed to beadditive and thus a sum for all the performed passes and independent ofthe time difference between the passes. It thus means that for each passa calculation can be performed of the compaction effect exactly for thispass of the compacting operation on each unit area, after which thetotal effect is obtained as a sum of the calculated partial compactioneffects and the total compaction effect will then be indicated as ameasure of a compaction degree within the considered unit area of thedeposited layer.

The constant parameters of the compacting machine produces, at sometemperature of a deposited layer of asphalt, a compaction effect whichis supposed to be possible to calculate by means of the given anddetermined values. In FIG. 3 a diagram is showing how a simple weightfunction for the influence of the mass temperature could principally beconstructed. The curve has as an abscissa the temperature of the asphaltlayer and as an ordinate an estimated value of the compaction effect atthe respective temperature. The ordinate of the curve has its maximumvalue equal to 1 in a temperature interval which is ideal for the firstruns or passes. When the compaction effect deviates from the ideal valueequal to 1, the compaction effect of the pass is reduced and theordinate of the curve has a lower value. For a sufficient deviation evena negative value can be obtained even if it is not visible in the curvesof FIG. 3. In FIG. 3 a weight function is illustrated valid for the twofirst passes and another weight function for all following passes. In apreferred case, not illustrated here, even different weight functionscan be used for each one of the three first passes and a separate weightfunction for all the following passes. Weight functions of this kind canbe determined by experience and aided by experiments.

Similar curves can in a corresponding way be constructed for theinfluence of different compacting machine parameters such as rollingvelocity, amplitude and frequency, on the compaction result. Examplesare illustrated in FIGS. 4 and 5 where a weight curve is shown dependenton the movement speed of the compacting machine and dependent of thefrequency of the vibratory movement of a vibratory compacting machinerespectively. In a preferred embodiment also the weight curve accordingto FIG. 4 for the dependence on the movement speed can be replaced byfour different weight functions for both the three first passes and onefor the following ones.

The different values obtained from the ordinate value in curves of thekinds illustrated in the FIGS. 3-5 are multiplied by each other forobtaining a partial index number for a particular pass and a consideredunit area. Such a partial index number or number of points, which isdetermined for each individual pass, are then added successively for theproduction a total index number or a total number of points for eachunit area.

From FIG. 3 and the discussion accompanying it, it is obvious that thecompaction effect for a considered area segment and for a certain passdoes not uniquely depend on the temperature but also on the earlierhistory in compacting the segment, i.e. in this case on the order numberof this pass.

The partial contribution to the total index number which is obtained fora considered area segment and for a certain pass, generally depends on

1. Variable or measurable variables such as

the temperature of the deposited material,

changeable parameters of the compacting machine such as the movementspeed, the vibratory frequency, the vibratory amplitude.

2. Parameters which are constant for a compacting work in the depositionof the material at a definite occasion, such as

constants for the mass such as type of material, thickness of thedeposited layer,

constants for the compacting machine such as type of compacting machine,line load, radius of the rolling drum, and

weather and wind.

3. The early history of the considered area segment in the shape of

the degree in which the paving machine compacts the material whendepositing the material,

the number of passes run before the considered pass,

time intervals between the passes,

values of variables for the passes earlier run.

From earlier experience in compacting earth at constant other conditionsit is known that the total index number R of the compaction increasesapproximately proportionally to the logarithm of the number (p) ofpasses or runs, see FIG. 8. The partial index E for a certain passhaving order number p can then be ##EQU1##

It can be assumed that the ground or surface layer is completelyuncompacted before the first pass. Normally a certain precompactionoccurs or is present which is produced by the paver of the material. Itvaries depending on the type of paver machine, such as if it is of typerammer, vibrating skid, etc. In order to describe the effect of acertain compacting machine pass, the partial index for a pass having theorder number p can then instead be written ##EQU2## where p₀ is ameasurement of the precompaction degree expressed in the number ofequivalent compacting machine passes.

A consideration of the generally reduced compacting effect for laterpasses has already been made for the curves in the diagram according toFIG. 3, where the maximum value of the weight curve for passes havingorder number from and including the third pass is smaller than themaximum value for the weight curve valid for the two first passes. Itcan however be advantageous to separate these two effects, so that thecurves of FIG. 3 all will have the same maximum value, e.g. equal to 1,which is illustrated by the curve drawn in dotted lines for passes fromand including the third one. Like above then, for obtaining the partialindex number for a certain considered unit area, the various factors aremultiplied which are obtained from curves of the type as illustrated inFIGS. 3, 4, and 5, and also a general reduction factor obtained fromequation (2) with a suitable choice of the constant p₀.

In FIG. 6 in the top diagram, the total index number is shown for aconsidered area segment as a function of time. In the bottom diagram thetemperature of the asphalt within this area segment is shown as afunction of time. The temperature curve is a continuously decreasingfunction and the total index number increases stepwise for each passwhich is performed at the times t₁ -t₄, where larger steps are used forthe first passes, when the asphalt has a low degree of compaction andstill is hot, and smaller steps for the later passes.

On the monitor 19 and within the area segments of the different paths orlanes, which are passed by the compacting machine, the calculated totalnumber of points for each unit area or unit distance is illustrated witha varying light intensity such as with a grey scale. The greyness ofeach area segment can be shown as representing the ratio of the achievedtotal number of points to a minimum number of points which is to beachieved for the asphalt layer in order that the compaction thereofshould be considered as acceptable. The surface portions passed by thecompacting machine are shown in the monitor pictures of FIGS. 2A and 2Bat the top in varying grey shades and at the bottom in these picturesthe homogenous grey area portion represents a ground surface which isnot compacted but is located "in front" as seen in the depositingdirection for the layer. Such an equally grey surface portion is notrepresented in FIG. 2C since this monitor picture is valid for a timewhere the compacting machine during this operation has had time tocompact a longer longitudinal region. FIGS. 2A-2C thus show thecompaction result at three successive times. Instead of usingintensities in a grey scale also colours of a suitable colour scale canbe used if a colour monitor is used. Another alternative can be to usedigital number values of the total index number for each area segment.

The driver of the compacting machine can use this information comprisedin the varying greyness of the display picture to adjust the velocity ofthe compacting machine, the length of stroke for displacement withineach path or lane and possibly other compacting machine parameters tooptimize the result of the compacting work, in particular to achieve thedesired minimum total number of points for each area segment. The drivercan also demand or request a lower velocity of the paver in the case itappears that he cannot achieve a sufficient compaction number of points,or contrarily, request the paver to increase its velocity, in the casewhere the minimum number of points for the compaction degree is easilyobtained and thus an excess of the compaction capacity of the compactingmachine exists.

At the top of the screen at 35 the number value are shown representingthe total index number achieved up to now and the partial index numberfor exactly that area segment over which the compacting machine nowpasses, and at the bottom, the number of the pass, as calculated fromand including the first one, which is currently being performed by thecompacting machine.

Before the start of the deposition of an asphalt layer and compactionthereof by means of the compacting machine, (for documentation of theobject and to form a base for the calculation of weight curves) projectidentification and project data are entered, as well as data for thecompacting machine, data for the asphalt layer such as type, thethickness, etc. thereof, and the planned velocity of the paver, whichinformation in all its essential parts is stored in the memory 17. Seein particular the top fields in the list of FIG. 7. Most of these valuesneed not be changed as long as the compacting machine performs the sametype of compaction work. Before each work pass the driver of thecompacting machine must, however, enter the starting section and furtheruse the arrow keys 31 on the monitor 19 to adjust the present positionof the compacting machine in relation to the asphalt paver, i.e. whichpath or lane on which the compacting machine stands, and the distance ofthe compacting machine to the paver in meters. Then the driver depresseskey 33 for start/stop when the paver starts to deposit asphalt. Duringthe pass then, in the fields illustrated at the bottom in FIG. 7, thevarious measured and determined parameters are stored as a function ofthe position of the compacting machine, i.e. parameters for eachposition of the compacting machine, which is for instance given by thesegment as indicated in meters within a path or lane and path numberwith a numbering of the paths e.g. from the left in the monitor picturesof FIGS. 2A-2C. The parameters can comprise the measured temperature,the movement velocity of the compacting machine over the area segment,vibration or no vibration or for vibration the vibratory frequency andamplitude, the calculated partial index number for this pass. Further,also the total calculated index number is stored for each area segment,in the Figure in the record represented by the row having the name"Total", entered in the field for the number of the pass. Data enteredin the Figure are indicated by dots (.).

The compacting machine thus passes the first present path or lane,performs a change of direction and when the compacting machine the firsttime changes its direction at a place close to the paver machine, thedriver of the compacting machine should (if needed) adjust the positionof the compacting machine symbol 25 in relation to the symbolrepresenting the paver 21. For each succeeding change of direction at aplace close to the paver the calculating unit 1 calculates the averagevelocity of the paver as taken from the previous change of directionclose to the paver and then updates the corresponding number valueshowed within the paver machine symbol 21 on the monitor 19.Alternatively, the signal from a distance measuring device 11 and/orinformation in regard of the velocity of the paver as obtained form theunit 12 (FIG. 1A) can be used for a determination of correct positionsand distances.

It can be mentioned that if all of the weight functions as mentionedabove are given the constant value 1 over the definition regionsthereof, also the function E (compare equation (2)), which only dependson the order number of the passes, on the monitor 19 in the differentpaths or lanes, fields will be indicated having grey shades of varyingintensities indicating only the number of passes which have been madeover each unit area. It can be of value for a rapid evaluation of thecompacting work.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art wereintended to be included within the scope of the following claims.

I claim:
 1. A method for measurement of the compaction degree of asegment of a deposited layer of hot asphalt, which continually coolsafter the deposition thereof and is compacted by being passed repeatedlyby a compacting machine, the method comprising the steps of:calculatingasphalt segment values which are valid only for each pass made by saidcompacting machine; calculating a total index number as a function ofthe asphalt segment values for all the passes made as a measure of thecompaction degree of each segment; and controlling said compactingmachine according to said asphalt segment values and said total indexnumber to provide uniform compacting of said asphalt.
 2. The methodaccording to claim 1, wherein the calculating the total index numberstep further comprises the steps of:calculating a partial index numberas a function of the asphalt segment values valid only for each saidpass; and calculating the total index number by the sum of the partialindex numbers of successive passes.
 3. The method according to claim 2,further comprising the steps of:measuring temperature of each saidasphalt segment at each said pass; and calculating the partial indexnumber as a function of the temperature of each said asphalt segment ateach said pass.
 4. The method according to claim 2, further comprisingthe steps of:measuring a velocity of the compacting machine at each saidpass; and calculating the partial index number for each said asphaltsegment as a function of the movement velocity at each said pass of eachsaid asphalt segment.
 5. The method according to claim 2, furthercomprising the steps of:calculating at least one of a vibratoryfrequency and a vibratory amplitude of the compacting machine; andcalculating the partial index number for each said asphalt segment as afunction of at least one of the vibratory frequency and the vibratoryamplitude respectively at each said pass of the compacting machine overeach said asphalt segment.
 6. The method according to claim 1, whereinthe calculating the total index number step further comprises the stepsof:calculating a partial index number as a function of the asphaltsegment values valid only for each said pass; measuring temperature ofeach said asphalt segment at each said pass; and calculating the partialindex number as a function of the temperature of each said asphaltsegment at each said pass;wherein the total index number is a product offunctions; each function depending only on one of said asphalt segmentvalues.
 7. The method according to claim 1, further comprising the stepsof:continuously depositing asphalt layers which are in a hot state by apaving machine in front of the compacting machine; passing over eachsaid asphalt segment behind the paving machine to compact each saidasphalt segment by said compacting machine; calculating for each saidasphalt segment deposited by the paving machine and passed by thecompacting machine, the total index number as a function of the asphaltsegment values measured for each said asphalt segment and of operationalparameters of the compacting machine; and controlling travel of thecompacting machine over each said asphalt segment and the operationalparameters of the compacting machine so that the total index number foreach said asphalt segment achieves at least a predetermined value. 8.The method according to claim 7, further comprising the stepsof:repeatedly passing areas behind the paving machine by said compactingmachine, calculating a partial index number for each said asphaltsegment for each said pass of the compacting machine over each saidasphalt segment as a function of the asphalt segment values measured foreach said asphalt segment and of the operational parameters of thecompacting machine; and calculating the total index number for each saidasphalt segment as a sum of the partial index numbers determined foreach said pass of each said asphalt segment.
 9. The method according toclaim 7, further comprising the steps of:continuously calculating thetotal index number for each said asphalt segment; and displaying saidtotal index number to an operator of the compacting machine.
 10. Themethod according to claim 9, further comprising the steps of:displayingthe total index number for each said asphalt segment on a display;displaying at least one of said partial and said total index numbers ofeach said asphalt segment as fields having a location on the displaywhich corresponds to and is proportional to actual locations of eachsaid asphalt segment; and displaying the fields with at least one oflight and colour intensity which is proportional to the total indexnumber calculated for each said asphalt segment, the colour intensityincluding colours chosen in a colour scale, the scale being arranged tocorrespond to a plurality of total index numbers, the colour beingchosen so that the fields correspond to the calculated total indexnumber of each said asphalt segment.
 11. A device for measurement of thecompaction degree of a segment of a deposited layer of hot asphalt,which continually cools after the deposition thereof and is compacted bybeing repeatedly passed by a compacting machine, the devicecomprising:first means for determination of asphalt segment values foreach pass over each said asphalt segment, said values are valid only foreach said pass; and calculating means for determination of a total indexnumber as a measure of the compaction degree of each said asphaltsegment, said total index number being a function of the asphalt segmentvalues for all passes made over each said segment, whereby saidcompacting machine is controlled according to said asphalt segmentvalues and said total index number to provide uniform compacting of saidasphalt.
 12. The device according to claim 11, wherein the calculatingmeans determines for said each pass a partial index number as a functionof the asphalt segment values determined by the first means, and saidcalculating means determines the total index number as a function onlyof the sum of the partial index numbers of successive passes.
 13. Thedevice according to claim 12, wherein the first means for determinationcomprises means on the compacting machine for measurement of atemperature of each said segment when each said segment is passed overby the compacting machine; and the calculating means determines thepartial index number of each said segment as a function of temperatureof each said segment at a corresponding pass.
 14. The device accordingto claim 12, wherein said first determination means includes a devicewhich measures movement velocity of the compacting machine and thecalculating means determines the partial index numbers as a function ofthe movement velocity as measured for the compacting machine at acorresponding pass.
 15. The device according to claim 11, furthercomprising:a paving machine in front of the compacting machinecontinuously depositing layers of asphalt, the compacting machinerepeatedly passing and compacting each said asphalt segment behind thepaving machine; the calculating means determines for each said asphaltsegment deposited by the paving machine and passed by the compactingmachine said total index number as a function of the asphalt segmentvalues determined for each said asphalt segment by the first means fordetermination and of operational parameters of the compacting machine;and display means in a driver's cabin in the compacting machine fordisplaying said total index number of each said asphalt segment passedby the compacting machine in order to control travel of the compactingmachine over individual asphalt segments and to control the operationalparameters of the compacting machine so that said total index number foreach said asphalt segment achieves at least a predetermined value. 16.The device according to claim 15, wherein the display means shows saidtotal index number for each said asphalt segment in the shape of a fieldin an area on said display means which corresponds to and isproportional to an actual position of each said asphalt segment, thefields being shown with at least one of light and colour intensity whichis proportional to said total index number calculated for each saidasphalt segment, asphalt segments shown on said display means with acolour are selected in accordance with a colour scale, the scale beingarranged to correspond to the various possible values of said totalindex number, and the colour being chosen so that the fields correspondto said total index number of each said asphalt segment.
 17. The methodaccording to claim 2, further comprising the step of:calculating saidpartial index number according to the equation: ##EQU3## where E is thepartial index number; p is an order number for one pass; and p_(O) is ameasurement of a precompaction degree expressed in a number ofequivalent compacting machine passes.
 18. The device according to claim12, wherein said calculating means determines said partial index numberaccording to the equation: ##EQU4## where E is the partial index number;p is an order number for one pass; and p_(O) is a measurement of aprecompaction degree expressed in a number of equivalent compactingmachine passes.